U.S. patent number 9,266,054 [Application Number 13/868,838] was granted by the patent office on 2016-02-23 for durable adsorbent material and adsorbent packs and method of making same.
This patent grant is currently assigned to Micropore, Inc.. The grantee listed for this patent is Micropore, Inc.. Invention is credited to Nicholas J. Dunlop, Douglas B. McKenna.
United States Patent |
9,266,054 |
McKenna , et al. |
February 23, 2016 |
Durable adsorbent material and adsorbent packs and method of making
same
Abstract
Provided herein are a parallel passage contractors, which may be
useful in pressure swing adsorption (PSA), pressure and temperature
swing adsorption (PTSA), or vacuum pressure swing adsorption (VPSA)
systems, having one or more self-supported adsorbent sheets
arranged in multiple, overlapping layers mechanically spaced to
allow gas flow. Also provided are systems utilizing such parallel
passage contactors and methods for preparing the contactors.
Inventors: |
McKenna; Douglas B. (Avondale,
PA), Dunlop; Nicholas J. (Wilmington, DE) |
Applicant: |
Name |
City |
State |
Country |
Type |
Micropore, Inc. |
Elkton |
MD |
US |
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Assignee: |
Micropore, Inc. (Elkton,
MD)
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Family
ID: |
49378903 |
Appl.
No.: |
13/868,838 |
Filed: |
April 23, 2013 |
Prior Publication Data
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Document
Identifier |
Publication Date |
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US 20130276634 A1 |
Oct 24, 2013 |
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Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
Issue Date |
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61637517 |
Apr 24, 2012 |
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Current U.S.
Class: |
1/1 |
Current CPC
Class: |
B01J
20/08 (20130101); B01J 20/2803 (20130101); B01J
20/2804 (20130101); B01J 20/28026 (20130101); B01D
53/02 (20130101); B01D 53/0423 (20130101); B01J
20/28042 (20130101); B01J 20/18 (20130101); B01D
53/047 (20130101); B01J 20/20 (20130101); B01D
53/0462 (20130101); B01D 2253/34 (20130101); B01D
53/0476 (20130101) |
Current International
Class: |
B01D
53/047 (20060101); B01D 53/04 (20060101); B01D
53/02 (20060101) |
Field of
Search: |
;96/121,153,154
;55/520 |
References Cited
[Referenced By]
U.S. Patent Documents
Foreign Patent Documents
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171551 |
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EP |
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1064979 |
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Jan 2001 |
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EP |
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WO 01/07114 |
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Feb 2001 |
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WO |
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WO 2005/086613 |
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Sep 2005 |
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WO |
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WO 2006/025853 |
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Mar 2006 |
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WO |
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WO 2007/117266 |
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Oct 2007 |
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WO |
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WO 2009/152264 |
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Dec 2009 |
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WO |
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WO 2010/129082 |
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Nov 2010 |
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WO |
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WO 2011/094296 |
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Aug 2011 |
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WO |
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WO 2012/051524 |
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Apr 2012 |
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WO |
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Primary Examiner: Lawrence; Frank
Attorney, Agent or Firm: Fish & Richardson P.C.
Parent Case Text
This application claims the benefit of priority of U.S. Provisional
Appl. 61/637,517, filed Apr. 24, 2012, which is incorporated herein
by reference in its entirety.
Claims
What is claimed is:
1. A system for pressure swing adsorption (PSA) or vacuum pressure
swing adsorption (VPSA), comprising a parallel passage contactor
structure comprising one or more self-supported adsorbent sheets
arranged in multiple, overlapping layers mechanically spaced to
allow gas flow between said layers from one end of the structure to
the other, wherein said one or more adsorbent sheets are formed by
a thermally induced phase separation process from a mixture
comprising adsorbent particles selected from molecular sieves,
activated alumina, zeolites, and activated carbon; and a polymer
binder; wherein the adsorbent particles in said sheet are of one or
more types and each type of adsorbent particles have a mean
particle size of greater than 200 nm; wherein said binder comprises
0.5% to 5% by weight of the sheet.
2. The system of claim 1, wherein the adsorbent particles are of a
single type and have a mean particle size of greater than 200
nm.
3. The system of claim 1, wherein said structure remains
mechanically stable after 200,000 or 1,000,000 pressure swing
cycles.
4. The system of claim 1, wherein said adsorbent sheets have
substantially parallel ribs disposed on said one or more sheets,
which mechanically space said layers to allow gas flow.
5. The system of claim 1, wherein said parallel contactor structure
comprises a single spirally wound adsorbent sheet having
substantially parallel ribs disposed on said sheet, wherein said
ribs mechanically space said layers to allow gas flow.
6. The system of claim 1, wherein said binder comprises 0.5% to 4%
by weight of said sheet.
7. The system of claim 1, wherein said binder comprises 0.5% to 3%
by weight of said sheet.
8. The system of claim 1, wherein said binder comprises 0.5% to 2%
by weight of said sheet.
9. The system of claim 1, wherein said binder comprises about 0.5%
to 1% by weight of said sheet.
10. The system of claim 1, wherein said binder is a thermally
induced phase separated polyethylene.
11. The system of claim 1, wherein said binder is a thermally
induced phase separated high-density polyethylene.
12. The system of claim 1, wherein said binder is a thermally
induced phase separated ultra high molecular weight
polyethylene.
13. A parallel passage contactor structure configured for use in
pressure swing adsorption (PSA) or vacuum pressure swing adsorption
(VPSA), comprising one or more self-supported adsorbent sheets
arranged in multiple, overlapping layers mechanically spaced to
allow gas flow between said layers from one end of the structure to
the other, wherein said one or more adsorbent sheets are formed by
a thermally induced phase separation process from a mixture
comprising adsorbent particles selected from molecular sieves,
activated alumina, zeolites, and activated carbon, a polymer
binder, and aramid or carbon reinforcement fibers, which have a
mean length of no more than 500 um on their longest side; wherein
said binder comprises 0.5% to 5% by weight of the sheet and said
reinforcement fibers comprise 0.1% to 10% by weight of the
sheet.
14. The parallel passage contactor structure of claim 13, wherein
said reinforcement fibers no more than about 5%, no more than about
2% or no more than about 1% by weight of the adsorbent sheet.
15. The parallel passage contactor structure of claim 13, wherein
said binder comprises from 0.5% to 2% by weight of said sheet.
16. The parallel passage contactor structure of claim 13, wherein
the adsorbent sheet has a decreased Gurley Densometer, Model 4340
automatic Gurley Densometer time by comparison to a structure
without reinforcement fibers.
17. The parallel passage contactor of claim 13, wherein said
adsorbent sheets have substantially parallel ribs disposed on said
one or more sheets, which mechanically space said layers to allow
gas flow.
18. The parallel passage contactor of claim 13, wherein said
parallel contactor structure comprises a single spirally wound
adsorbent sheet having substantially parallel ribs disposed on said
sheet, wherein said ribs mechanically space said layers to allow
gas flow.
19. The parallel passage contactor of claim 13, wherein said
contactor is up to 48 inches in height.
20. The parallel passage contactor of claim 13, wherein the
reinforcement fibers have a mean length of 10 um to 250 um on their
longest side.
21. A system for pressure swing adsorption (PSA), comprising the
parallel passage contactor of claim 13.
22. The parallel passage contactor structure of claim 13, wherein
said binder is a thermally induced phase separated
polyethylene.
23. The parallel passage contactor structure of claim 13, wherein
said binder is a thermally induced phase separated high-density
polyethylene.
24. The parallel passage contactor structure of claim 13, wherein
said binder is a thermally induced phase separated ultra high
molecular weight polyethylene.
Description
FIELD OF THE INVENTION
The present invention relates to adsorbent materials, adsorbent
packs, methods of making an adsorbent material and/or adsorbent
pack, and methods of enriching and/or reducing a gas.
BACKGROUND
Self-supporting adsorbent materials comprising adsorbent particles
and a binder are used in a wide variety of applications. Some
applications however, such as pressure swing adsorption, are very
demanding and currently available adsorbent materials lack
sufficient strength and durability without high binder content.
Pressure swing adsorption adsorbents are typically packed beds of
adsorbent granules with different shapes that have many
shortcomings. These adsorbent materials physically degrade from the
damaging effects of pressure swing cycles. In addition, because of
the high pressure drop through beds of granules, the flow rate must
be kept low to minimize lifting of the granules from the packed
beds. This high pressure drop also limits the allowable height of
the adsorbent bed, which limits the time between pressure swing
cycles, thereby reducing efficiency of the system. Replacement of
damaged adsorbent beds requires the system to be shut down further
increasing in use costs. Finally, the beads distribution may not be
uniform resulting in low and high flow areas across the surface of
the packed bed, which results in systems that must be larger than
desired to account for large performance variations.
There exists a need for an adsorbent material and adsorbent pack
that has high strength and durability, as well as high adsorbent
particle concentration and high gas adsorption rate. In particular,
there exists a need for an adsorbent material and adsorbent pack
that is suitable for pressure swing adsorption applications, having
high durability and high gas adsorption properties.
SUMMARY OF THE INVENTION
In some embodiments, a system for pressure swing adsorption (PSA),
pressure and temperature swing adsorption (PTSA), or vacuum
pressure swing adsorption (VPSA) is provided, comprising a parallel
passage contactor (PPC) structure comprising one or more
self-supported adsorbent sheets arranged in multiple, overlapping
layers mechanically spaced to allow gas flow between said layers
from one end of the structure to the other, wherein said one or
more adsorbent sheets comprises adsorbent particles and a polymer
binder; wherein the adsorbent particles in said sheet can be of one
or more types and each type of adsorbent particles have a mean
particle size of greater than 200 nm. In some embodiments, the
adsorbent sheet is made by a thermally induced phase separation
process. In some embodiments, the polymer is a polyethylene binder.
In some embodiments, the adsorbent particles are of a single type
and have a mean particle size of greater than 200 nm. In some
embodiments, self-supported means that the sheets do not require a
backing. In some embodiments, the adsorbent sheets are reinforced
by fibers formed during the making of the sheets (e.g., are
self-reinforced). The sheets are generally flexible enough to allow
winding of the sheet to form a spirally wound PPC structure. In
some embodiments, wherein said adsorbent sheets have substantially
parallel ribs disposed on said one or more sheets, which
mechanically space said layers to allow gas flow. In some
embodiments, the parallel contactor structure comprises a single
adsorbent sheet, which is spirally wound, having substantially
parallel ribs disposed on said sheet, wherein said ribs
mechanically space said layers to allow gas flow. In some
embodiments, the PPC structure consists essentially of said
adsorbent particles and said polyethylene binder. In some
embodiments, the PPC structure additionally comprises reinforcement
fibers as described herein. In some embodiments, the adsorbent
sheet is less than 0.10 inches, 0.09 inches, less than 0.08 inches,
less than 0.07 inches, less than 0.06 inches or less than 0.05
inches in thickness, including the ribs. In some embodiments, the
thickness of the sheet, excluding the ribs is from 0.01 to 0.06
inches. In some embodiments, the thickness of the ribs disposed on
the sheet is from 0.01 to 0.04 inches.
In some embodiments, the PPC structure is mechanically stable after
200,000 or 1,000,000 cycles.
In some embodiments, the binder comprises 0.25% to 10%, 0.25% to
9%, 0.25% to 8%, 0.25% to 7%, 0.25% to 6%, 0.25% to 5%, 0.25% to
4%, 0.25% to 3%, 0.25% to 2%, or 0.25% to 1% by weight of said
sheet. In some embodiments, the binder is high-density polyethylene
or ultra high molecular weight polyethylene. In some embodiments,
the binder comprises 0.5% to 1%, 0.5% to 2%, 0.5% to 3%, 0.5% to
4%, 0.5% to 5%, 0.5% to 6%, 0.5% to 7%, 0.5% to 8%, 0.5% to 9%,
0.5% to 10%, 0.5% to 15%, or 0.5% to 20% by volume of the adsorbent
material which is formed into the sheet. In some embodiments, the
binder is a thermally induced phase separated polyethylene. In some
embodiments, the binder is thermally induced phase separated
high-density polyethylene or a thermally induced phase separated
ultra high molecular weight polyethylene.
In some embodiments, adsorbent particles are molecular sieves,
activated alumina, zeolites, or activated carbon. In some
embodiments, the adsorbent particles form at least 75%, 80%, 85%,
90%, 95%, 96%, 97%, 99%, or 99.5% by weight of said sheet. In some
embodiments, the adsorbent particles form at least 30%, 35%, 40%,
45%, 50%, 55%, 60%, 65%, 70%, or 75%, by volume of adsorbent
material which is formed into the sheet. In some embodiments, the
adsorbent particles are interconnected by the polymer binder to
form a self-supporting porous adsorbent. In some embodiments, at
least 20%, at least 30%, at least 40%, at least 50%, at least 60%,
at least 70%, at least 80%, at least 90%, at least 95% or at least
100% of the adsorbent particles are interconnected by the polymer
binder. In some embodiments, the binder forms elongated sections
with a mean length to diameter ratio of greater than or equal to
1/2, 2/1, 5/1, 10/1, 50/1, 100/1 or 200/1. In some embodiments, the
binder forms a thermoplastic network with said particles, wherein
said network has porosity.
In one embodiment, a parallel passage contactor (PPC) structure is
provided, comprising one or more self-supported adsorbent sheets
arranged in multiple, overlapping layers mechanically spaced to
allow gas flow between said layers from one end of the structure to
the other, wherein said one or more adsorbent sheets comprises
adsorbent particles, a polymer binder, and reinforcement fibers. In
some embodiments, the PPC structure is configured for use in
pressure swing adsorption (PSA), pressure and temperature swing
adsorption (PTSA), or vacuum pressure swing adsorption (VPSA). In
some embodiments, the PPC structure is configured for use in
removal of gaseous contaminants (including, but not limited to,
carbon dioxide (CO.sub.2), carbon monoxide (CO), volatile organic
compounds (VOCs), chemical or biological toxicants, sulfur dioxide,
hydrogen sulfide, chlorinated compounds or water vapor).
Non-limited applications include generating an air stream,
including, but not limited to, enclosed spaces. Markets that can
benefit from the disclosed apparatus and method include, but are
not limited to, diesel-electric powered submarines, nuclear
submarines, safety shelters (CBRN--chemical, biological,
radiological, and nuclear), hyperbaric chambers, powered mine
shelters, industrial gas separation and purification processes, and
other industrial gas adsorbent systems, and rebreather systems,
such as SCUBA rebreathers, personnel protection systems and
firefighter rebreathers.
In some embodiments, reinforcement fibers can be carbon fibers
(activated or non-activated), aramid fibers, glass fibers, or other
fibers that would structurally reinforce the adsorbent sheet. In
some embodiments, the reinforcement fibers are carbon fibers. In
some embodiments, the carbon fibers can be activated carbon fiber
or non-activated carbon fibers. In some embodiments, the carbon
fibers are activated carbon fibers. In some embodiments, the fibers
are aramid fibers. In some embodiments, the aramid fibers are
carbonized aramid fibers. In some embodiments, the reinforcement
fibers have a mean length of greater than 100 microns on their
longest side, a mean length of not greater than 0.01 inches on
their longest side, a mean length of not greater than 0.02 inches
on their longest side, a mean length of not greater than 0.03
inches on their longest side, or a mean length on their longest
side of not greater than 50%, 40%, 30%, 20%, 10%, 5%, 4%, 3%, 2%,
or 1% of the thickness of the adsorbent sheet. In some embodiments,
the reinforcement fibers have a mean length of 10 um to 250 um, 10
um to 200 um, 10 um to 100 um, or 15 to 100 um on their longest
side. In some embodiments, the reinforcement fibers are no more
than about 50%, no more than about 40%, no more than about 30%, no
more than about 20%, no more than about 10%, no more than about 5%,
no more than about 2%, no more than about 1% by weight of the
adsorbent sheet. In some embodiments, the reinforcement fibers are
no more than about 50%, no more than about 40%, no more than about
30%, no more than about 20%, no more than about 10%, no more than
about 5%, no more than about 2%, no more than about 1% by volume of
the adsorbent material which is formed into said sheet. The
reinforcement fibers may be incorporated into the adsorbent
material, including into the integral adsorbent retention layer. In
one embodiment, the reinforcement fibers are incorporated only into
the adsorbent material and in another embodiment, the reinforcement
fibers are incorporated only into the integral adsorbent retention
layer. Reinforcement fibers may increase the mechanical strength
and durability of the adsorbent material. For example, the matrix
tensile strength, the compressive strength, or compressive modulus
of the adsorbent material may be substantially increase by the
addition of reinforcement fibers. The reinforcement fibers may be
added at any suitable time in the process of making the adsorbent
material, including during the mixing process, during the extrusion
process, during the cooling and thermally induced phase separation
process, during the calendaring process, and the like.
In some embodiments, wherein said adsorbent sheets have
substantially parallel ribs disposed on said one or more sheets,
which mechanically space said layers to allow gas flow. In some
embodiments, the parallel contactor structure comprises a single
adsorbent sheet, which is spirally wound, having substantially
parallel ribs disposed on said sheet, wherein said ribs
mechanically space said layers to allow gas flow.
In some embodiments, the PPC structure comprises: (a) a plurality
of parallel, non-wound adsorbent surfaces, mechanically spaced so
as to allow gas flow between each surface in the plurality; and (b)
one or more fasteners, wherein the one or more fasteners secures
the plurality of said surfaces together. In some embodiments, the
cartridge comprises square adsorbent sheets arranged into a cube.
In some embodiments, the cartridge comprises round or oval
adsorbent sheets arranged into a cylinder. In some embodiments, the
cartridge comprises triangular or trapezoidal sheets arranged into
a solid block of adsorbent. In some embodiments, the cartridge
comprises rectangular adsorbent sheets arranged into a rectangular
stack. In some embodiments, the PPC structure can be arranged as
shown in US 2011/0206572, which is incorporated herein by reference
in its entirety. In some embodiments, the PPC structure can be
arranged as shown in U.S. Pat. No. 5,964,221, which is incorporated
herein by reference in its entirety.
The adsorbent particles may be any of the adsorbent particles
described herein and may be of the sizes described herein.
In some embodiments, the binder is a polyethylene binder or other
binder described herein. In some embodiments, the binder comprises
0.25% to 10%, 0.25% to 9%, 0.25% to 8%, 0.25% to 7%, 0.25% to 6%,
0.25% to 5%, 0.25% to 4%, 0.25% to 3%, 0.25% to 2%, or 0.25% to 1%
by weight of said sheet. In some embodiments, the binder is
high-density polyethylene or ultra high molecular weight
polyethylene. In some embodiments, the binder comprises 0.5% to 1%,
0.5% to 2%, 0.5% to 3%, 0.5% to 4%, 0.5% to 5%, 0.5% to 6%, 0.5% to
7%, 0.5% to 8%, 0.5% to 9%, 0.5% to 10%, 0.5% to 15%, or 0.5% to
20% by volume of the adsorbent material which is formed into the
sheet. In some embodiments, the binder is a thermally induced phase
separated polyethylene. In some embodiments, the binder is
thermally induced phase separated high-density polyethylene or a
thermally induced phase separated ultra high molecular weight
polyethylene.
In some embodiments, the reinforcement fibers allow the PPC
structure to have a height of greater than 6 inches, or from 12
inches to 36 inches, from 12 inches to 48 inches, from 18 inches to
36 inches or 18 inches to 48 inches, or a height of 48 inches or
less.
The absorbent may be a single absorbent or a mixture of different
adsorbents. In some embodiments, the adsorbent includes, but is not
limited to, calcium hydroxide (Ca(OH).sub.2), lithium hydroxide
(LiOH), calcium hydroxide mixed with a percentage of sodium and
potassium hydroxide, other CO.sub.2 adsorbents and mixtures
thereof. In some embodiments, the adsorbent (e.g., calcium
hydroxide) is mixed with other alkali metal hydroxides such as
sodium hydroxide or potassium hydroxide. In some embodiments,
adsorbent particles are molecular sieves, activated alumina,
zeolites, or activated carbon. In some embodiments, the adsorbent
particles form at least 75%, 80%, 85%, 90%, 95%, 96%, 97%, 99%, or
99.5% by weight of said sheet. In some embodiments, the adsorbent
particles form at least 30%, 35%, 40%, 45%, 50%, 55%, 60%, 65%,
70%, or 75%, by volume of adsorbent material which is formed into
the sheet. In some embodiments, the adsorbent particles are
interconnected by the polymer binder to form a self-supporting
porous adsorbent. In some embodiments, at least 20%, at least 30%,
at least 40%, at least 50%, at least 60%, at least 70%, at least
80%, at least 90%, at least 95% or at least 100% of the adsorbent
particles are interconnected by the polymer binder.
In another embodiment, a parallel passage contactor structure is
provided, comprising one or more self-supported adsorbent sheets
arranged in multiple, overlapping layers mechanically spaced to
allow gas flow between said layers from one end of the structure to
the other, wherein said one or more adsorbent sheets comprises
adsorbent particles selected from molecular sieves, activated
alumina, zeolites, or activated carbon, 0.1% to 5% by weight of a
polyethylene binder, and 0.1 to 40% by weight of carbon or aramid
fibers having a mean length of greater than 100 microns on their
longest side, configured for use in pressure swing adsorption
(PSA), pressure and temperature swing adsorption (PTSA), or vacuum
pressure swing adsorption (VPSA). The fibers can be any of those
described herein in any of the weight or volume percentages
described herein. In some embodiments, the carbon fibers are
activated carbon fibers. In some embodiments, the carbon fibers are
non-activated carbon fibers. In some embodiments, the aramid fibers
are carbonized aramid fibers. In some embodiments, the fibers are
aramid fibers. In some embodiments, the fibers comprise 0.1% to
30%, 0.1% to 20%, 0.1% to 10% or 0.1% to 5% by weight of said
sheet. In some embodiments, the polyethylene binder comprises 0.1%
to 5%, 0.1% to 4%, 0.1% to 3%, 0.1% to 2% or 0.1% to 1% by weight
of said sheet. In some embodiments, the fibers comprise 0.1% to
30%, 0.1% to 20%, 0.1% to 10% or 0.1% to 5% by volume of the
adsorbent material which is formed into the sheet. In some
embodiments, the polyethylene binder comprises 0.5% to 10%, 0.5% to
9%, 0.5% to 8%, 0.5% to 7%, 0.5% to 6%, 0.5% to 5%, 0.5% to 4%,
0.5% to 3%, 0.5% to 2% or 0.5% to 1% by volume of the adsorbent
material which is formed into the sheet.
In one embodiment, a system is provided, comprising any of the
parallel passage contactor structures or articles described herein.
In some embodiments, the system is a pressure swing adsorption
(PSA), pressure and temperature swing adsorption (PTSA), or vacuum
pressure swing adsorption (VPSA) system. In some embodiments, the
systems is for use in removal of gaseous contaminants (including,
but not limited to, carbon dioxide (CO2), carbon monoxide (CO),
volatile organic compounds (VOCs), chemical or biological
toxicants, sulfur dioxide, hydrogen sulfide, chlorinated compounds
or water vapor). Non-limited applications include generating an air
stream, including, but not limited to, enclosed spaces. Markets
that can benefit from the disclosed apparatus and method include,
but are not limited to, diesel-electric powered submarines, nuclear
submarines, safety shelters (CBRN--chemical, biological,
radiological, and nuclear), hyperbaric chambers, powered mine
shelters, industrial gas separation and purification processes, and
other industrial gas adsorbent systems, and rebreather systems,
such as SCUBA rebreathers, personnel protection and personnel
escape systems and firefighter rebreathers.
In some embodiments, self-supporting means that the article or
structure means the sheet can hold its shape without need of a
backing, laminate support, external support, or internal
reinforcement.
In some embodiments, an article (which may be in the form of a
parallel passage contactor) is provided, comprising:
adsorbent particles;
a polymer binder; and
a plurality of integral channels;
wherein the adsorbent particles are interconnected by the polymer
binder to form a self-supporting porous adsorbent that is
configured for forced fluid flow through said integral channels.
The article has high strength and durability for demanding
applications, such as pressure swing adsorption (PSA), pressure and
temperature swing adsorption (PTSA), or vacuum pressure swing
adsorption (VPSA). In some embodiments, the forced fluid flow
comprises at least one gas molecule for adsorption and at least one
gas for enrichment.
Also provided is an article (which may be in the form of a parallel
passage contactor), comprising:
adsorbent particles;
an oriented polymer binder; and
a plurality of integral channels;
wherein the adsorbent particles are interconnected by the polymer
binder to form a self-supporting porous adsorbent that is
configured for forced fluid flow through said integral
channels;
wherein said article is made by a thermally induced phase
separation process comprising the steps of:
dissolving said polymer binder in a first solvent to form a
mixture;
adding and mixing adsorbent particles with said mixture to form an
adsorbent slurry;
extruding said adsorbent slurry to from an extrudate;
cooling extrudate to cause thermally induced phase separation;
forming said integral channels in said extrudate; and drying said
extrudate.
Additionally provided is an article (which may be in the form of a
parallel passage contactor) comprising an adsorbent sheet suitable
for forced fluid flow consisting essentially of:
adsorbent particles;
a thermoplastic oriented polymer binder; and
at least one integral channel;
wherein the adsorbent particles are interconnected by the polymer
binder to form a self-supporting porous adsorbent that is
configured for forced fluid flow through said channel.
In another embodiment, an article (which may be in the form of a
parallel passage contactor) is provided comprising a fluid
enrichment device comprising:
1) an adsorbent pack comprising one or more adsorbent sheets
comprising:
adsorbent particles;
an oriented polymer binder; and
a plurality of integral channels; wherein the adsorbent particles
are interconnected by the polymer binder to form a self-supporting
porous adsorbent that is configured for forced fluid flow through
said integral channels;
2) a housing;
wherein the adsorbent pack is at least partially enclosed by the
housing, and wherein the housing is configured for fluid flow there
through.
In some embodiments, the adsorbent sheet described herein is
self-supporting having a porous structure of adsorbent particles
interconnected by a polymer binder. The polymer binder may be
oriented between adsorbent particles and be elongated having an
aspect ratio of at least 2:1. In one embodiment, the adsorbent
material is made by a thermally induced phase separation process.
The adsorbent sheet can be arranged to form a plurality of integral
channels. Adsorbent sheets may be configured into an adsorbent pack
or cartridge, and a fluid, such as a gas, may be forced through the
adsorbent pack. In one application, an adsorbent pack is configured
in a pressure swing adsorption process where a gas is passed
through the integral channels of the adsorbent pack, and the
pressure is changed throughout the process. At least one gas
molecule may be adsorbed by the adsorption particles and one or
more gas molecules of a different type may pass through the
adsorbent pack. A gas may be enriched by passing the gas through
the adsorbent pack, wherein at least one of the gases is increased
in concentration by at least one molecule as the gas passes through
the adsorbent pack described herein.
The adsorbent material described herein may be substantially liquid
resistant, and/or substantially water resistant. Any suitable
fluid, such as a gas or liquid may be passed through the integral
channels of the adsorbent pack, or over the adsorbent material
described herein. The adsorbent sheet may be non-permeable, having
substantially no bulk air flow through the material. For example,
in one embodiment, the adsorbent material is a sheet having a
Gurley Densometer time of more than 100 seconds (e.g., as measured
on a Gurley Densometer, Model 4340).
In some embodiments, the adsorbent material comprises adsorbent
particles interconnected with polymer binder. Any number and type
of adsorbent particles may be used. The adsorbent particles may
have any suitable shape and size and are typically no more than
about 250 um in size. One or more types of adsorbent particles may
be incorporated into the adsorbent material in any suitable ratio,
or weight percentage.
The adsorbent material comprises polymer binder that interconnects
the adsorbent particles by contacting the adsorbent particles and
extending to another adsorbent particle. The polymer may be
branched between the adsorbent particles as defined herein. Any
suitable percentage of the adsorbent particles may be
interconnected with the polymer such as, but not limited to, at
least about 20%, at least about 30%, at least about 40%, at least
about 50%, at least about 60%, at least about 70%, at least about
80%, at least about 90%, at least about 95%, at least about 99%,
and between and including any of the values provided. The adsorbent
sheet material made by a thermally induced phase separation process
having a uniquely high percentage of adsorbent particles
interconnected with polymer, such as at least about 50% or
more.
The adsorbent particles may be any suitable size including, but not
limited to, no more than about 200 um (um=micrometer or micron), no
more than about 100 um, no more than about 50 um, no more than
about 25 um, no more than about 10 um, no more than about 5 um, and
any range between and including the size dimensions provided. In
some embodiments, the adsorbent particles have a mean particle size
of greater than 200 nm. The adsorbent particles may comprise any
type or combination of suitable materials, including inorganic
compounds, zeolites, activated carbon, molecular sieves, and the
like. In some embodiments, the adsorbent particles are calcium
hydroxide, lithium hydroxide, or calcium hydroxide mixed with a
percentage of sodium and potassium hydroxide. In some embodiments
the adsorbent particles are. In some embodiments, the adsorbent
particles are not calcium hydroxide or lithium hydroxide particles.
In some embodiments, the adsorbent particles consist essentially of
one type of adsorbent material.
The polymer binder may be any suitable type or combination of
materials including, but not limited to, thermoplastics, soluble
polymers, ultra high molecular weight polymers, ultra high
molecular weight polyethylene, polytetrafluoroethylene, urethane,
elastomer, fluoroelastomer and the like. In some embodiments, the
polymer binder may be oriented, wherein it is elongated between,
and interconnects adsorbent particles and has an aspect ratio of at
least 2:1. Oriented polymer may significantly increase the strength
of the adsorbent material. Any suitable percentage of the polymer
binder may be oriented as defined herein, including, but not
limited to, at least about 10%, at least about 40%, at least about
50%, at least about 60%, at least about 70%, and any range between
and including the values provided. In one embodiment, the polymer
binder is substantially oriented, wherein at least 70% of the
polymer is oriented. The oriented polymer may have any suitable
aspect ratio, including but not limited to, greater than about 2:1,
greater than about 3:1, greater than about 5:1, greater than about
10:1, greater than about 25:1, greater than about 40:1, greater
than about 50:1, and any range between and including the aspect
ratios provided. In addition, the oriented polymer may have any
suitable diameter or maximum cross length dimension including, but
not limited to, no more than about 5 um, no more than about 2 um,
no more than about 1 um, no more than about 0.5 um, and any range
between and including the dimensions provided.
The oriented polymer binder may be substantially aligned in the
same direction, wherein the long axis of the oriented polymer
binder are all substantially aligned. For example, in one
embodiment the adsorbent material comprises oriented polymer binder
that is substantially aligned in the processing direction of the
material.
The polymer content of the adsorbent material may be any suitable
percentage by weight including, but not limited to, no more than
about 10%, no more than 8%, no more than 5%, no more than 4%, no
more than 3%, no more than 2%, no more than 1%, no more than 0.6%,
and any range between and including any of the provided percentages
by weight. In some embodiment, the polymer binder is between 0.5 to
2%, 0.5 to 3% or 0.5 to 4% by weight. Low concentration of polymer
means a higher concentration of adsorbent particles which may
increase adsorption capabilities including rate and quantity.
The adsorbent material is porous, allowing for the diffusion of gas
into the structure whereby specific gas molecules may be adsorbed
by the adsorbent particles. The adsorbent may have any suitable
porosity including, but not limited to, more than about 5%, more
than about 10%, more than about 20%, more than about 30%, more than
about 50%, more than about 60%, more than about 70%, more than
about 80%, more than about 90%, more than about 95%, and any range
between and including the percentages provided. Likewise the
adsorbent material may have any suitable density including, but not
limited to, no more than about 2 g/cc, no more than about 1.5 g/cc,
no more than about 1 g/cc, no more than about 0.75 g/cc, no more
than about 0.5 g/cc, no more than about 0.3 g/cc, no more than
about 0.2 g/cc, and any range between and including the densities
provided. The density of the adsorbent material will be affected by
the adsorbent particle type, concentration and porosity of the
adsorbent material.
The adsorbent sheet may have a first surface and a second surface
and any suitable thickness including, but not limited to, no more
than about 1 mm, no more than about 2 mm, no more than about 4 mm,
no more than about 6 mm, and the like. The adsorbent sheet may be a
continuous sheet of material having a length greater than about 3
meter, greater than about 10 m, greater than about 100 m, greater
than about 1,000 m, and any range between and including the lengths
provided.
The adsorbent sheet may comprise a plurality of integral channels,
having the same or different dimensions. In one embodiment, the
channels are only on one side of the sheet, and in another
embodiment the channels are on both sides of the sheet. The
channels may be aligned with the processing direction of the
adsorbent sheet material, or may be configured at an angle to the
processing direction, such as perpendicular to the procession
direction. The channels may be linear, may be curved, or may be
configured with at least a portion that is curved. The channels may
be branched or may intersect each other along the length of the
adsorbent material. The channels may have a depth that is any
suitable percentage of the overall thickness of sheet including but
not limited to, more than about 20%, more than about 40%, more than
about 50%, more than about 60% more than about 70%, more than about
80%, and any range between and including the percentages provided.
The channels may have a width of any suitable ratio to the depth
dimension including, but not limited to, more than about 0.5:1,
more than about 0.75:1, more than about 1:1, more than about 1.5:1,
more than about 2:1, more than about 3:1, more than about 4:1, and
any range between and including the ratios provided. In one
embodiment, the channels may be uniform along the channel length,
such as from the inlet to the outlet of the adsorbent pack. In
another embodiment, the flow channels may have a cross sectional
area that varies along the length of the channel, such as from the
inlet to the outlet. In yet another embodiment, the channels may
all have substantially the same configuration along the length of
the channel, such as a rectangular shape that is linear, for
example. In still another embodiment, the channels may have
different configurations along the length of the channel, but may
have substantially the same pressure drop from the inlet to the
outlet. Any number of different configurations of channels and
combinations of configurations described herein have been
envisioned.
The adsorbent sheet may further comprise an integral adsorbent
retention layer on at least one surface, and may be on both
surfaces. In one embodiment, the integral adsorbent retention layer
is not within the surface of the integral channels described
herein. An integral adsorbent retention layer is a thin layer of
partially occluded pores on the surface of an adsorbent sheet. The
integral adsorbent retention layer may comprise smeared polymer
binder material and adsorbent material. In one embodiment, the
integral adsorbent retention layer consists essentially of polymer
binder and may be smeared or comprise a thin film layer of polymer
binder. The integral adsorbent retention layer may occlude any
suitable percentage of the surface of the adsorbent material
including but not limited to no more than about 90%, no more than
about 80%, no more than about 70%, no more than about 60%, no more
than about 50%, no more than about 40%, and any range between and
including any of the percentages provided. The integral adsorbent
retention layer may have open areas having any suitable nominal
pore size including but not limited to no more than about 50 um, no
more than about 25 um, no more than about 10 um, no more than about
5 um, no more than about 3 um, no more than about 2 um, no more
than about 1 um, and any range between and including any of the
pore sizes provided. The integral adsorbent retention layer may
have any suitable thickness including but not limited to, no more
than about 5 um, no more than about 3 um, no more than about 2 um,
no more than about 1 um, no more than about 0.75 um, no more than
about 0.5 um, and any range between and including the thickness
values provided.
The adsorbent sheets described herein may be made into a adsorbent
pack, including adsorbent cartridges having a height and diameter.
In another embodiment, the adsorbent sheets may be stacked, folded,
pleated or otherwise configured into an adsorbent pack. The
adsorbent pack may be in the form of a sheet arranged to form a
plurality of integral channels, and the sheet may be spirally wound
to create an adsorbent pack having a plurality of flow paths, or
channels there through. In another embodiment, discrete sheets of
adsorbent material may be stacked with integral channels configured
and aligned to provide a flow path through the pack. An adsorbent
pack may be used to enrich a gas by passing a fluid through the
integral channels having a first gas that is adsorbed, and a second
gas or multiple other gases that are not adsorbed or are less
strongly adsorbed. The adsorbent material may be selected to either
only adsorb a particular gas molecule or adsorb much more of, or at
a higher rate, a specific gas molecule.
The adsorbent packs as described herein may be used in any
adsorption and/or enrichment process. In one embodiment, the
adsorbent pack is configured for pressure swing adsorption
processes. Pressure swing adsorption process may have any suitable
flow rate and pressure range. The adsorbent pack of the present
invention may be made to fit directly into existing adsorbent
housings or into frames which can accept and seal adsorbent packs
into existing pressure vessels.
The adsorbent material and pack of the present invention may be
made through any suitable set of procession steps. In one
embodiment, the adsorbent sheet, as described herein, is made by a
thermally induced phase separation process by dissolving a polymer
binder in a first solvent (e.g., mineral oil) at elevated
temperature to form a mixture, adding and mixing adsorbent
particles with the mixture to form an adsorbent slurry, extruding
the adsorbent slurry to form an extrudate or sheet, cooling the
extrudate to induce thermally induced phase separation, forming
integral channels in the extrudate, using a second solvent to
remove said first solvent, and drying said extrudate to form an
adsorbent sheet having integral channels. The channels may be
formed in the adsorbent sheet through any suitable process. For
example, an extrudate may be passed through a calendaring roll
having a profile that forms integral channels in the sheet as it
passes there through. In another embodiment, discrete sheets may be
pressed with a platen to form the integral channels. In yet another
embodiment, integral channels may be machined into an adsorbent
sheet before or after it is dried. For example, a series of
grinding wheels may be used to remove adsorbent material from a
sheet and therein form the adsorbent sheet with integral
channels.
The summary of the invention is provided as a general introduction
to some of the embodiments of the invention, and is not intended to
be limiting. Additional example embodiments including variations
and alternative configurations of the invention are provided
herein.
BRIEF DESCRIPTION OF THE DRAWINGS
The accompanying drawings are included to provide a further
understanding of the invention and are incorporated in and
constitute a part of this specification, illustrate embodiments of
the invention, and together with the description serve to explain
the principles of the invention
FIG. 1A shows a schematic of the adsorbent material as described
herein.
FIG. 1B shows a schematic of the adsorbent material comprising
oriented polymer binder as described herein.
FIG. 1C shows a schematic of the adsorbent material comprising
aligned oriented polymer binder as described herein.
FIG. 2A shows a cross-sectional schematic of the adsorbent material
comprising an integral adsorbent retention layer as described
herein.
FIG. 2B shows a surface schematic of the adsorbent material
comprising an integral adsorbent retention layer described
herein.
FIG. 3A shows a surface schematic of the adsorbent material
comprising reinforcement fibers as described herein.
FIG. 3B shows a cross-section schematic of the adsorbent material
comprising reinforcement fibers as described herein.
FIG. 4A shows an isometric view schematic of the adsorbent material
comprising integral channels as described herein.
FIG. 4B shows a cross-section schematic of the adsorbent material
comprising integral channels as described herein.
FIG. 5 shows an isometric view schematic of the adsorbent material
comprising integral channels at offset angles as described
herein.
FIG. 6A shows an isometric view schematic of the adsorbent material
comprising integral channels on both the first and second surface
of the adsorbent material as described herein.
FIG. 6B shows an enlarged view of the isometric view schematic of
FIG. 6A.
FIG. 7 shows a cross-section view of a adsorbent pack in a housing
as described herein.
FIG. 8 shows an isometric view of an adsorbent cartridge as
described herein.
FIG. 9 shows a process schematic for making the adsorbent material
described herein.
FIG. 10 shows an embodiment of a parallel passage contactor or
adsorbent pack with nylon spacer rings and sealant.
FIG. 11 shows an embodiment of a parallel passage contactor or
adsorbent pack with tie rod to assist with positioning and removal
of the contactor or pack during testing or use.
FIG. 12 is a self-supported adsorbent cartridge in which part of
the adsorbent volume has been removed (for illustration purposes)
to expose the stakes securely fastening the adsorbent sheets.
DETAILED DESCRIPTION
Certain exemplary embodiments of the present invention are
described herein and illustrated in the accompanying figures. The
embodiments described are only for purposes of illustrating the
present invention and should not be interpreted as limiting the
scope of the invention. Other embodiments of the invention, and
certain modifications, combinations and improvements of the
described embodiments, will occur to those skilled in the art and
all such alternate embodiments, combinations, modifications,
improvements are within the scope of the present invention. The
embodiments depicted in the Figures are embodiments and are not
limiting. It is intended that the embodiments described herein can
be combined in any suitable combination as if written in multiply
dependent claims.
The adsorbent material 10 of the present invention comprises
adsorbent particles 12, 12' interconnected with polymer binder 14,
14' as shown in FIG. 1A. Some of the polymer binder may contact
both adsorbent surfaces as shown in 14' and may not be oriented as
described herein. The adsorbent material 10 comprises polymer
binder 14 that interconnects the adsorbent particles 12 by
contacting the adsorbent particles and extending to another
adsorbent particle 12', as shown in FIG. 1A. The polymer binder 14
may be branched wherein a first portion of polymer may be connected
with a second portion of polymer between two or more particles, as
show in FIG. 1B. Any suitable percentage of the adsorbent particles
may be interconnected with the polymer as described herein. A
higher concentration of adsorbent particles may provide improved
adsorption performance. In one embodiment, the adsorbent material
is made by a thermally induced phase separation process, and
comprises a uniquely high percentage of adsorbent particles by mass
or volume relative to polymer content, and interconnected with said
polymer.
As shown in FIGS. 1A, and 1B, substantially all of the adsorbent
particles are interconnected by polymer binder. In addition, as
shown in FIG. 1B, some of the polymer binder is oriented polymer
binder 42, wherein it is elongated between and interconnecting
adsorbent particles, and has an aspect ratio of at least 2:1 where
the length of the oriented polymer is shown as PBL in FIG. 1B.
Furthermore, as shown in the cross sectional schematic of the
adsorbent material in FIG. 1C, the oriented polymer binder is
aligned, or oriented substantially in the same direction, with a
majority of the oriented polymer binder being elongated in
substantially the same direction. Substantially the same direction,
as used herein, means within a 30 degree inclusive angle of the
average oriented polymer binder direction. The arrow over the
adsorbent material in FIG. 1C represents the process direction of
the material. This aligned orientation of the polymer binder may be
imparted during the processing of the material, such as during
extrusion, roll to roll transfer between process steps, during
calendaring, during integral channel formation, or during a
separate process step where the adsorbent material may be
elongated. Additionally, the polymer binder may be oriented in the
same plane as the machine direction, but perpendicular to the
machine direction.
Any number and type of adsorbent particles may be used. The
adsorbent particles may have any suitable shape and size. One or
more types of adsorbent particles may be incorporated into the
adsorbent material in any suitable ratio, or weight percentage. The
adsorbent particles may be any suitable size including, but not
limited to, no more than about 200 um, no more than about 100 um,
no more than about 50 um, no more than about 25 um, no more than
about 10 um, no more than about 5 um, and any range between and
including the size dimensions provided. The adsorbent particles may
comprises any type or combination of suitable materials, including
inorganic compounds, zeolites, activated carbon, lithium hydroxide,
calcium hydroxide, molecular sieves, 13.times. and the like. In
some embodiments, the adsorbent particles consist essentially of
one type of adsorbent material.
The polymer binder may be any suitable type or combination of
materials including, but not limited to, thermoplastics, soluble
polymers, ultra high molecular weight polymers, ultra high
molecular weight polyethylene, polytetrafluoroethylene, urethane,
elastomer, fluoroelastomer and the like. Oriented polymer binder
may significantly increase the strength of the adsorbent material.
Any suitable percentage of the polymer binder may be oriented as
defined herein, including, but not limited to, at least about 10%,
at least about 40%, at least about 50%, at least about 60%, at
least about 70%, and any range between and including the values
provided. In one embodiment, the polymer binder is substantially
oriented, wherein at least 70% of the polymer is oriented as shown
in FIG. 1B. The oriented polymer may have any suitable aspect
ratio, including but not limited to, greater than about 2:1,
greater than about 3:1, greater than about 5:1, greater than about
10:1, greater than about 25:1, greater than about 40:1, greater
than about 50:1, greater than 100:1 and any range between and
including the aspect ratios provided. In addition, the oriented
polymer may have any suitable diameter or maximum cross length
dimension including, but not limited to, no more than about 2 um,
no more than about 1 um, no more than about 0.5 um, and any range
between and including the dimensions provided.
The polymer content of the adsorbent material may be any suitable
percentage by weight including, but not limited to, no more than
about 10%, no more than about 8%, no more than about 5%, no more
than about 4%, no more than about 3%, no more than about 2%, no
more than about 1%, no more than about 0.6%, and any range between
and including any of the provided percentages by weight. Low
concentration of polymer means a higher concentration of adsorbent
particles which may increase adsorption capabilities including rate
and quantity.
The adsorbent material 10 is porous, allowing for the diffusion of
gas into the structure whereby specific gas molecules may be
adsorbed by the adsorbent particles. The adsorbent may have any
suitable porosity including, but not limited to, more than about
5%, more than about 10%, more than about 20%, more than about 30%,
more than about 50%, more than about 60%, more than about 70%, more
than about 80%, more than about 90%, more than about 95%, and any
range between and including the percentages provided. The adsorbent
material may be non-permeable, having substantially no bulk air
flow through the material. For example, in one embodiment, the
adsorbent material is a sheet having a Gurley Densometer, Model
4340 automatic Gurley Densometer time of more than 100 seconds, as
defined herein, or more than 25 seconds, or more than 50 seconds,
or more than 200 seconds, or more than 300 seconds, or more than
400 seconds. In some embodiments, the adsorbent sheet may have a
reduced Gurley time of less than 100 seconds (e.g., in some
embodiments, the sheet may comprise reinforcement fibers which may
open up the spacing between adsorbent particles). The adsorbent
sheet described herein is self-supporting having a porous structure
of adsorbent particles interconnected by polymer binder. As used
herein, the term self-supporting in reference to the adsorbent
material, means that the material is free-standing, or can be
handled without falling apart. Adsorbent packed beds for example
would not be self-supporting, as the adsorbent particles are loose
and require some external reinforcement or housing.
For packing of one size of spheres, the maximum theoretical packing
is 64% (36% void). Those skilled in the use of 13.times. molecular
sieve beads with a 4 to 8 mesh bead sieve size, find that with
proper filling of beads in a packed bed, one can achieve an inter
bead void volume of about 40%. Packing densities of fine powders to
produce spheres or adsorbents of the present invention, varies by
the amount of compaction or processing that has occurred, and also
by the shapes and sizes of the particles, which changes the
interparticle void volume.
In tests using thermally induced phase separation of ultra high
molecular weight polyethylene to produce calcium hydroxide sheets,
the interparticle void space as determined by oil content before
extraction is 68.0% void space. However after extracting this oil
with a solvent, and heating and removing the solvent, the adsorbent
sheet shrinks 18.3% by volume. If the maximum packing density of
calcium hydroxide powder has a void volume of 40%, then if one
starts with 68% void space, then 28% extra void volume is over and
above the maximum packing density form. If the total volume of the
adsorbent sheet shrinks by 18%, and this can only be accomplished
by reducing the extra void volume, then 18% divided by the initial
28% extra void volume, results in shrinking the extra void volume
by 64%. Even with this shrinkage, increased inter-particle void
volume is still achieved. In some embodiment, the fiber
reinforcement reduces the extra void space shrinkage, opening up
the inter-particle spacing and improving the macro-diffusion of
gases in the adsorbent structure. This may result in adsorbents
that have reduced gurley numbers, and increased utilization of
adsorbent particles contained in said adsorbent sheets.
The adsorbent sheet may further comprise an integral adsorbent
retention layer 50 on at least one surface, and may be on both
surfaces as depicted in FIGS. 2A and 2B. In one embodiment, the
integral adsorbent retention layer is not within the surface of the
integral channels described herein. An integral adsorbent retention
layer is a thin layer of material on the surface of an adsorbent
sheet. As shown in FIG. 2A and FIG. 2B, the integral adsorbent
retention layer 50 is very thin and discontinuous having openings
52 between portion of the integral adsorbent retention layer. The
openings 52 may be continuous as depicted in FIG. 2B, and/or
discrete, wherein they are defined by an outer boundary of the
integral adsorbent retention layer, such as a hole in the integral
adsorbent retention layer. The integral adsorbent retention layer
may comprise smeared polymer binder material and adsorbent
material. In one embodiment, the integral adsorbent retention layer
consists essentially of polymer binder and may be smeared or
comprise a thin film layer of polymer binder. The integral
adsorbent retention layer may occlude any suitable percentage of
the surface of the adsorbent material including but not limited to
no more than about 90%, no more than about 80%, no more than about
70%, no more than about 60%, no more than about 50%, no more than
about 40%, and any range between and including any of the
percentages provided. The integral adsorbent retention layer may
comprise openings 52 having any suitable nominal pore size
including but not limited to no more than about 100 um, no more
than about 50 um, no more than about 25 um, no more than about 10
um, no more than about 5 um, no more than about 3 um, no more than
about 2 um, no more than about 1 um, and any range between and
including any of the pore sizes provided. The integral adsorbent
retention layer may have any suitable thickness including but not
limited to, no more than about 5 um, no more than about 3 um, no
more than about 2 um, no more than about 1 um, no more than about
0.75 um, no more than about 0.5 um, and any range between and
including the thickness values provided.
In some embodiments, the adsorbent material may further comprise
reinforcement fibers 60 that may be incorporated into the adsorbent
material as depicted in FIGS. 3A and 3B. The reinforcement fibers
may be incorporated into any portion of the adsorbent material
including into the integral adsorbent retention layer. As depicted
in the surface schematic of FIG. 3A, the reinforcement fibers may
be disposed within the adsorbent material, and intertwine with the
polymer binder and adsorbent particles. The reinforcement fibers
may be concentrated within a plane of a sheet of adsorbent
material, such as on one surface. As shown in FIG. 3B, the
cross-section schematic depicts reinforcement fibers extending
through the thickness of the adsorbent material. The reinforcement
fibers may have a concentration gradient with the adsorbent
material, such as being concentrated on the surfaces and or within
the center of the thickness of the adsorbent material.
Reinforcement fibers may increase the mechanical strength and
durability of the adsorbent material. For example, the compressive
strength may be improved with reinforcing fibers, even when
increasing the distance between powder particles, thereby reducing
adsorbent material density, and reducing macro diffusion resistance
between adsorbent particles (by increasing the void space between
particles.
Any suitable amount of reinforcement fibers may be included into
the adsorbent material, and may comprise any suitable weight
percentage of the adsorbent material including, but not limited to,
no more than about 50%, no more than about 40%, no more than about
30%, no more than about 20%, no more than about 10%, no more than
about 5%, no more than about 2%, no more than about 1%, and any
range between and including the weight percentages provided. The
reinforcement fibers may have any suitable length and cross-length
dimension, such as diameter or width. The length of the
reinforcement fiber may be any suitable length including, but not
limited to, no more than about 0.01 mm no more than about 0.05 mm,
no more than about 0.10 mm, no more than about 0.25 mm, no more
than about 0.5 mm, no more than about 0.75 mm, no more than about 1
mm, no more than about 2 mm, no more than about 4 mm, no more than
about 8 mm, and any range between and including the lengths
provided. The width or maximum cross-length dimension may be any
suitable dimension including, but not limited to, no more than
about 0.1 um, no more than about 1 um no more than about 5 um, no
more than about 20 um, no more than about 50 um, no more than about
100 um, no more than about 500 um, and any range between and
including the lengths provided. The reinforcement fibers may be
added at any suitable time in the process of making the adsorbent
material, including during the mixing process, during the extrusion
process, during the calendaring process, and the like.
The adsorbent material 10 may be formed into a sheet 70 as shown in
FIGS. 4A and 4B, having a first surface 72 and a second surface 74
and any suitable thickness ASt including, but not limited to, no
more than about 1 mm, no more than about 2 mm, no more than about 4
mm, no more than about 6 mm, and any range between and including
the thickness values provided. The adsorbent sheet may be a
continuous sheet of material having a length greater than about 3
meter, greater than about 10 m, greater than about 100 m, greater
than about 1,000 m, and any range between and including the lengths
provided.
The adsorbent sheet may comprise a plurality of integral channels
80, having the same or different dimensions. The channels may have
any suitable width Cw and depth Cd as depicted in FIG. 4B. A rib 82
may separate channels as depicted in FIG. 4B. An integral channel,
as used herein, refers to a flow path into and out of the adsorbent
pack or cartridge. In some embodiments, no additional spacers may
be required. In one embodiment, the channels are only on one side
of the sheet, and in another embodiment, the channels are on both
sides of the sheet as shown in FIGS. 6A and 6B. The channels may be
aligned with the processing direction Pd of the adsorbent sheet 70
as shown in FIG. 4A, or may be configured at an angle to the
processing direction Pd as shown in FIG. 5. The channels may be
configured in any suitable orientation to the process directions,
such as in the process machine direction, or in the cross-machine
direction. The channels may be linear or may be curved or may be
configured with at least a portion that is curved. The channels may
be branched or may intersect each other along the length of the
material. The channels may have a depth that is any suitable
percentage of the overall thickness of sheet including but not
limited to, more than about 20%, more than about 40%, more than
about 50%, more than about 60% more than about 70%, more than about
80%, and any range between and including the percentages provided.
The channels may have a width of any suitable ratio to the depth
dimension including, but not limited to, more than about 0.5:1,
more than about 0.75:1, more than about 1:1, more than about 1.5:1,
more than about 2:1, more than about 3:1, more than about 4:1, and
any range between and including the ratios provided. Any number of
different configurations of channels and combinations of
configurations described herein have been envisioned.
The adsorbent material described herein may be made into an
adsorbent pack 90, including an adsorbent cartridge 92 having a
height and diameter as shown in FIG. 7 and FIG. 8 respectively. As
shown in FIG. 7, adsorbent sheets 70 have been stacked to form an
adsorbent pack 90 having integral channels 80 and placed into a
housing 100. As shown in FIG. 8, an adsorbent cartridge 92 has been
constructed from a continuous sheet 78 of adsorbent material 10
that has been wound. As depicted in FIG. 8 by the arrow, the flow
direction FD indicates in the inlet 94 and outlet 96 of the
cartridge. An adsorbent pack or cartridge may be used to enrich a
gas by passing a fluid through the integral channels having a first
gas that is adsorbed, and a second gas that is not adsorbed. The
adsorbent material may be selected to either only adsorb a
particular gas molecule or adsorb much more of, or at a higher
rate, a specific gas molecule.
FIG. 12 shows an embodiment of a self-supported adsorbent cartridge
141 containing adsorbent sheets 30 in which multiple stakes 142 and
143 (8 in the embodiment depicted in FIG. 12) are driven into the
adsorbent cartridge to securely hold the chemically reactive
adsorbent sheets together. A volume 145 demarcated by dashed lines
is removed from adsorbent cartridge 141 in FIG. 12 to expose stakes
142 and 143. These stakes enable the cartridge to maintain its
correct external dimensions while simultaneously holding each sheet
against the adjacent sheets. Alternatively, the adsorbent sheets
can be staked with a staple or staples, a wire, rod(s), a cord,
rivet(s), or elastic materials. The rigid staked cartridge may be
further wrapped with a thin polymer sleeve such that the sleeve
does not cover air inlet and outlet faces 146, 147 of the adsorbent
cartridge. This thin sleeve prevents the end user from contacting
the adsorbent chemical. The sleeve provides little or no clamping
forces to hold the adsorbent cartridge together.
In some embodiments no polymer sheet is wrapped around the
cartridge. The stakes rigidly hold the sheets in place such that
sheet to sheet contact is maintained. As shown in FIG. 12, stakes
142 are inserted perpendicular to flow path 144 and additional
cartridge stability can be achieved by inserting a stake or
multiple stakes 143 at angles up to at 90 degrees with respect to
flow path 144, which reduce or eliminate flexing of the cartridge.
Air inlet face 146 and air outlet face 147 of cartridge 141 can be
reversed should the direction of flow 144 be reversed. Cartridge
141 functions similarly for airflow from both directions.
Cartridge 141 can further include a wrap of polymer foam on four
sides of the cartridge to allow for sealing when cartridge 141 is
installed into a canister. The polymer foam could be installed by
itself or over or under a polymer wrap.
The adsorbent material and pack of the present invention may be
made through any suitable set of procession steps. In one
embodiment, the adsorbent material is made by a thermally induced
phase separation process as shown in FIG. 9, including the steps
of: dissolving a polymer binder in a first solvent at elevated
temperatures to form a mixture, adding and mixing adsorbent
particles with the polymer mixture to form an adsorbent slurry,
extruding the adsorbent slurry through a sheeting die to form an
extrudate or sheet, cooling the extrudate to cause thermally
induced phase separation, forming integral channels in the
extrudate, and extracting the first solvent from said extrudate to
form an adsorbent sheet having integral channels. The solvent may
be heated to any suitable temperature to cause the selected polymer
to dissolve.
The integral channels may be formed in the adsorbent sheet through
any suitable process. For example, an extrudate may be passed
through a calendaring roller having a profile that forms integral
channels in the sheet as it passes there through. In another
embodiment, discrete sheets may be pressed with a platen to form
the integral channels. In yet another embodiment, integral channels
may be machined into an adsorbent sheet before or after it is
dried. For example, a series of grinding wheels may be used to
remove adsorbent material from a sheet and therein form the
adsorbent sheet with integral channels.
An embodiment of the article was tested in a pressure swing
adsorption cycle test using the ISO 7183 standard, which captures
the key test parameters of inlet temperature, outlet temperature,
differential pressure, pressure dewpoint (chilled mirror
hydrometer), inlet pressure, outlet pressure, and flow rate. The
tested apparatus is analogous to that in FIG. 11, with the article
being a ribbed spirally wound adsorbent sheet formed from 13.times.
molecular sieves and an ultra high molecular weight polyethylene
binder made via a thermally induced phase separation process.
In a PSA rig (endurance testing on a moisture rig), the unit
completed approx 200,000 cycles and maintained a steady dewpoint
(typically -37 deg. C. PDP)
In the rapid cycle rig, the unit completed 1,000,000 cycles with no
real visible damage or deterioration in dew point, flow and
mechanical stability which was unexpected and is an improvement
over typical 13.times. molecular sieve 4 to 8 mesh beads with a 7
Bar pressure swing cycle. Even after being accidentally flooded,
the unit was able to reobtain optimal performance after purging
which was also unexpected, and would have required a system shut
down and adsorbent removal if this were to occur with standard
13.times., 4 to 8 mesh beads which are the current industry
standard.
In a cyclic test, results indicated the consistent
adsorption/desorption performance of the unit during the
pressure/temperature (PTSA) test. The rapid onset of equilibrium
(steady state conditions) after flooding was unexpected and a
potential improvement over other 13.times. molecular sieve based
systems.
It will be apparent to those skilled in the art that various
modifications, combination and variations can be made in the
present invention without departing from the spirit or scope of the
invention. Specific embodiment, features and elements described
herein may be modified, and/or combined in any suitable manner.
Thus, it is intended that the present invention cover the
modifications, combination and variations of this invention
provided they come within the scope of the appended claims and
their equivalents.
Continuous sheet as used herein is defined as a sheet of material
that may be made in long lengths, having a machine and cross
machine direction, wherein the machine direction may have a length
greater than about 3 meters, greater than about 10 meters, greater
than about 100 meters, greater than about 1000 meters, or between
and including any of the lengths provided.
Processing direction as used herein is defined as a direction that
is substantially parallel with either the machine or cross-machine
direction of the material.
Substantially non-permeable as used herein in reference to the
adsorbent material means that there is substantially no air flow
through the material, such as having a Gurley value of greater than
100 seconds.
Oriented polymer binder as used herein is defined as a polymer
binder that is elongated between, and interconnects adsorbent
particles and has an aspect ratio of at least 2:1.
Aspect ratio as used herein in reference to the oriented polymer
binder refers to the ratio of the length over the width, or maximum
cross-length dimension within the center 30% of the length.
The maximum cross-length dimension of oriented polymer binder is
the maximum dimension, width, diameter, etc, over the center 30% of
the length. To measure this value, measure the length of the
oriented polymer binder, find the center on an SEM image and then
measure over the center 30% of the length to determine the maximum
dimension.
As used herein, polymer binder consisting essentially of oriented
polymer binder means that the majority of the polymer binder is
elongated between, and interconnects adsorbent particles and has an
aspect ratio of at least 2:1.
* * * * *
References